Method and apparatus for installing a prepackaged piston assembly in an engine

ABSTRACT

This invention relates generally to a piston assembly and more specifically to a piston assembly in a prepackaged configuration. The prepackaged piston assembly is ready for immediate installation into an engine or compressor. The piston assembly has a plurality of rings preinstalled on a piston member and a sleeve position about the piston member and the plurality of rings maintaining the rings in a compressed position ready for installation into an engine. The piston assembly is lowered into a cylinder bore, the sleeve contacts the top surface of a block and the piston assembly can be easily installed into the cylinder bore without the need for the mechanic to compress the plurality of rings. Thus the present invention reduces time and expense required for rebuilding and engine and increases the quality of the rebuild.

[0001] This is a continuation-in-part of co-pending application SerialNo. 09,452,071, filed on Nov. 10, 1999.

TECHNICAL FIELD

[0002] This invention relates generally to an internal combustion engineand more specifically to prepackaged piston assemblies which areprovided with a plurality of piston rings positioned on each pistonmember and held in a compressed position.

BACKGROUND

[0003] Internal combustion engines have numerous components which needto be assembled in order to provide a complete engine. Engine repairfacilities, new engine manufacturers and engine re-manufactures areconstantly looking for ways to improve quality and reduce cost ofassembling engines. Many engine components are supplied by manufacturesother than the engine assembly facility. Engine components such as,pistons, rings, connecting rods and wrist pins are often packaged,shipped and stored separately at the engine manufacturer or assembler.Supplying engine components in this manner is costly, and increases theopportunity to damage components.

[0004] Additionally, when used engine components have undergone anexcessive amount of wear, the performance and efficiency of the engineis reduced. Engines which have undergone excessive wear are oftenrebuilt by replacing major components. Many of the components that arenormally replaced during the rebuilding process include pistons, pistonrings, connecting rods, rod bearings, and main bearings. This rebuildingof the engine brings the engine back to or near, the enginemanufacturer's original performance or specifications. To insure thequality of the rebuilt engine the rebuild process is preferably done ina controlled environment such as a factory or repair shop.

[0005] Often with large machines utilizing internal combustion engines,such as those used in the construction and mining industry, the size ofthe machine restricts transportation to an engine rebuild shop, or thetime permitted for the rebuild process requires that the engine of themachine be rebuilt in the field. Often when engines are rebuilt thequality of the rebuild may be jeopardized due to incorrect inspection orassembly of major components such as pistons and piston rings. Loss ofquality may increase with engines which are rebuilt in the field underless than an ideal controlled environment.

[0006] Additionally the amount of time required to prepare componentssuch as piston assemblies for the rebuild process may be significantlygreater in a repair shop or the field than if the same work is done in afactory where larger quantities of components are assembled andmanufacturing processes and procedures can be systematically followed.Often in the factory, repetitive work is performed at lower labor costthan where the same work is performed by a skilled mechanic in thefield.

[0007] The present invention overcomes many of the above identifiedproblems by providing piston assemblies which have been inspected andassembled in a factory environment and packaged in a manner whichreduces the likelihood of quality related problems. Labor cost toassemble an engine may also be reduced by eliminating the number ofsteps to assemble the engines.

SUMMARY OF THE INVENTION

[0008] In one aspect of the invention a piston assembly has aprepackaged configuration and is adapted for use with an engine. Theengine is comprised of a piston member with a plurality of ring grooves.A plurality of rings are positioned in the ring grooves. A sleeve ispositioned about the piston member and the plurality of rings,maintaining the plurality of rings in a compressed position. A containeris positioned about the piston member, plurality of rings, and thesleeve.

[0009] In another aspect of the invention a method of assembling apiston assembly in an engine is disclosed. The piston assembly has aprepackaged configuration and comprises a piston member with a pluralityof rings thereon and a sleeve positioned around the piston assembly andthe plurality of rings. The sleeve maintains the plurality of rings in acompressed position. The method of assembly comprises the followingsteps. Removing the piston assembly from a container. Positioning thepiston assembly in alignment with a cylinder bore. Removing the pistonassembly from the sleeve. And, simultaneously inserting the pistonassembly into the cylinder bore. The sleeve is discarded after thepiston assembly has been installed into the engine.

[0010] In another aspect of the invention a sleeve adapted for use witha piston assembly of an engine is provided. The sleeve includes a topsurface, a bottom surface and an outer wall. A window is provided in theouter wall.

[0011] In another aspect of the invention a method is provided formanufacturing a sleeve for use with a piston assembly having apre-packaged configuration is provided. The method includes the steps ofproviding a tube having a predetermined inside diameter, removing alength of the tube and providing a window in the removed tube.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a partially sectioned view of an engine having aprepackaged piston assembly partially installed therein;

[0013]FIG. 2 is a exploded view of a piston assembly and components ofthe prepackaged configuration;

[0014]FIG. 3 is a perspective view of a plurality of piston assemblieswithout connecting rods arranged in a shipping container.

[0015]FIG. 4 is a top view of a of a plurality of pre-packaged pistonassemblies arranged on a shipping container.

[0016]FIG. 5 is a perspective view of a sleeve, or ring compressor, formaintaining the rings of the prepackaged piston assembly in thecompressed position; and

[0017]FIG. 6 is a perspective view of a second embodiment of the sleevefor maintaining the rings of a prepackaged piston assembly in thecompressed position.

[0018]FIG. 7 is a perspective view of a strap for use as an alternateembodiment of a sleeve.

[0019]FIG. 8 is a partially sectioned view of an embodiment of analternate sleeve and latching member.

[0020]FIG. 9 is a partially sectioned view of an embodiment of analternate sleeve and latching member.

[0021]FIG. 10 is a partially sectioned view of an embodiment of analternate sleeve and latching member.

[0022]FIG. 11 is a partially sectioned view of an embodiment of analternate sleeve and latching member.

DETAILED DESCRIPTION

[0023] Although this embodiment of the present invention refers to useof a piston assembly 10 in a prepackaged configuration 12 for use withan internal combustion engine 14, it should be recognized that theinvention is equally as valuable in use with an air compressor or othermachines using piston assemblies.

[0024] Referring first to FIG. 1, the engine 14 is illustrated as apartially sectioned view of an engine block 16. A portion of aprepackaged piston assembly 18 is also shown. The block 16 defines a topsurface 20 and a pair of outer walls 24 extending downward from each endof the top surface 20. A cylinder bore 26 extends downward from the topsurface 20. The cylinder bore 26 may be positioned in a replaceableliner or a fixed bore in the engine block 16. In this application, awater jacket 28 is interposed the cylinder bore 26 and the outer walls24; however, as an alternative the engine 14 could be air cooled.

[0025] The prepackaged piston assembly 18 as best shown in FIG. 2 iscomprised of a piston assembly 10 a sleeve 30 and a container 32. Thepiston assembly 10 has a piston member 36 having a top portion 38 and anouter surface 40 defined on the piston member 36. A plurality of ringgrooves 42 are positioned in the outer surface 40 below the top portion38 and a plurality of rings 46 are inserted in the ring grooves 42. Theplurality of rings 46 define a ring spread 48. The ring spread 48 can bedefined as an axial distance between the top of a top ring groove 50 andthe bottom of a bottom ring groove 52. A wrist pin bore 54 extendsthrough the outer surface 40 of the cylindrical piston member 36. A snapring groove 58 is defined within the wrist pin bore 54 near each end. Asan alternative the piston assembly 10 may further have a connecting rod60. The connecting rod 60 is affixed to the piston member 36 in aconventional manner by using a wrist pin 62. A lubricant and or rustinhibitor may be applied to all or some surfaces of the pre-packagedpiston assembly 18.

[0026] In the prepackaged configuration 12 of the piston assembly 10,the sleeve 30 is positioned about the piston member 38 and the pluralityof rings 46. The sleeve 30 maintains the plurality of rings 46 in acompressed position. The pre-packaged piston assembly 18 may in be anindividual configuration, or may be in a multiple configuration as shownif FIGS. 3 and 4. The pre-packaged piston assembly 18 may include theconnecting rod 60 although it is not required.

[0027] The sleeve 30 may be manufactured in a number of ways. Preferablythe sleeve 20 is manufacture from a material and in a manner that wouldminimize cost. As further shown in FIG. 5, a perspective view of onesleeve 30 of the present invention is illustrated. The sleeve 30 has atop surface 64 a bottom surface 66 and an outer wall 68. A sleeve bore70 (or inner wall) extends between the top surface 64 and the bottomsurface 66. A window 74 may extend from the outer wall 68 to the sleevebore 70. An alternative to the window 74 is a sleeve being made from atransparent material. The sleeve bore 70 is of a predetermined insidediameter 76 which is equal to or slightly smaller than the diameter ofthe cylinder bore 26 and slightly larger the outside diameter 78 of thepiston member 36.

[0028] As further shown in FIG. 6, another embodiment of the sleeve 30is shown. The sleeve 30 has a top surface 64 a bottom surface 66 and anouter wall 68. A sleeve bore 70 is defined between the top surface 64and the bottom surface 66. The sleeve bore 70 defines a straight portion80 extending from the bottom surface 68 toward the top surface 66. Atapered portion 82 of the sleeve bore 70 extends outwardly from a topend 84 of the straight portion 80 to the top surface 64. The length ofthe straight portion 80 is at least equal to the ring spread 48 of thepiston member 36.

[0029] Referring now to FIGS. 7-11, an alternate sleeve 30′ may beformed from a substantially flat strap 86. The formed sleeve 30′provides a variable inside diameter 90 that is substantially equal tothat of the piston member 36. The flat strap 86 includes a sleeveportion 88 having predetermined width 92 at a first end 94 of the strap86. Additionally, the sleeve portion 88 includes a predetermined length95. The predetermined length 95 must be at least equal to thecircumference of the piston member 36 that the sleeve 30 will be usedon. A second end 96 has a narrower width than that of the predeterminedwidth 92. The predetermined width 92 is equal to or greater than thering spread 48 of the piston member 36. A latching member 100 isprovided near the first end 94. The latching member 100 is adapted toreceive the second end 96, to form the sleeve 30′. The latching member100 is preferably adapted to varying the inside diameter 76 of thesleeve 30′.

[0030] The latching member 100 may be provided in a variety ofconfigurations. Some examples of latching members 100 are describedhereafter, but it should be noted that any number of conventionallatching members are suitable, yet not described.

[0031] An embodiment of a latching member 100 is illustrated in FIG. 8,and is similar to that of a plastic wire tie. The latching member 100includes a body portion 102. The body portion 102 has a slot 104 definedtherein. At least one barb 108 (or catch) is disposed within the slot104. A mating portion 110 of the strap 86 is adapted to be positionedwithin the slot 104. The mating portion 110 may include a frictionportion 112. The friction portion 112 illustrated in FIG. 7 is aplurality of ribs 114 disposed along a surface 116 of the strap 86. Thefriction portion 110 is configured to permit movement of the matingportion 110 relative to the slot 104.

[0032] Referring now to FIG. 9, an embodiment for the latching member100 is similar to that used to adjust the size of a hat. Near the firstend 94 of the strap 86 a plurality of openings 120 are spacedpredetermined distance from one and other. On the first end 94 of thestrap 86 one or more protrusions 122 extend outward from the surface 116of the strap 86. The protrusions 122 include a body portion 124 and ahead portion 126. The body portion 124 of the protrusion 122 is of aslightly smaller diameter than that of the head portion 126. At leastone of the protrusions 122 and at least one of the openings 120 areadapted to engage one and other and form a sleeve 30 of the appropriateinside diameter 76.

[0033] Referring now to FIG. 10, an embodiment of a latching member 100is illustrated. The body portion 102 is defined near the first end 94 ofthe strap 86. The body portion 102 also includes the slot 104 and isadapted to receive the second end 96. Within the body portion 102 arotatable cam 130 is disposed, and pivotable between a first and secondposition. The cam 130 includes a lever portion 132 adapted to rotate thecam 130. In the first position the second end 96 of the strap 86 ismoveable within the slot 104. With the cam 130 in the second position,the second end 96 is fixedly interposed the cam 130 and the slot 104.

[0034] Referring now to FIG. 11, an embodiment of the latching member100 having a wedge member 134 is illustrated. The wedge member 134 ispositioned within the slot 104 and moveable between a first position anda second position. In the first position the second end 96 of the strap86 is moveable within the slot 104. With the wedge member 134 in thesecond position the second end 96 of the strap 86 is fixedly interposedthe slot 104 and the wedge member 134.

[0035] Referring again to FIG. 2, in the prepackaged configuration 12,the pre-packaged piston assembly 18 is sealed in the container 32. Inthis embodiment the container is a plastic bag 138. The plastic bag 138is coated on the inside with a rust inhibitor and/or lubricant. Theplastic bag 138 defines a cavity 140 which is capable of accommodatingthe prepackaged configuration 12 of the piston assembly 10.Alternatively of the plastic bag 138, a flexible sheet having aprotective coating and a seal 142 could be used. The flexible sheet maybe constructed of many different materials including, but not limitedto, paper, waxed paper and plastic. The flexible sheet may additionallybe coated or impregnated with the rust inhibitor and/or lubricant.

[0036] Referring again to FIGS. 3 and 4, a plurality of pre-packagedpiston assemblies 18 arranged in a single shipping container is shown.The piston assemblies 10 may include the connecting rod 60 asillustrated in FIG. 4. As shown in FIG. 3, the piston assemblies 10 maybe packaged without the connecting rod 60. The piston assemblies 10 maybe coated with the lubricant and/or rust inhibitor as previouslydiscussed. A foam sheet having a plurality of cavities 158 that areshaped to fit the piston assemblies 10 may be used. Alternately,conventional packing materials may surround all or part of the pistonassemblies 10. The second container 144 may further be adapted toreceive a plurality of layers of piston assemblies 10. Each of theplurality of layers may be positioned on a tray 162 that is adapted tohold the packing materials and piston assemblies 10. Sheets of plasticor paper having a protective coating may be wrapped around the pistonassemblies 10. The sheets of plastic or paper may also be coated withthe lubricant and/or rust inhibitor. The second container 144 and/or thesheets may further be hermetically sealed.

[0037] Referring again to FIG. 2, a second container 144 may also beprovided but is not required in the present invention. The secondcontainer 144 illustrated in FIG. 2 has a cylindrical configuration, butas an alternative could have other shapes such as a square or octagonalconfiguration. The second container 144 has a container wall 150 and abottom 152. An opening 154 in a top end of the second container 144 isclosable. For example, a cap (or a top) 156 can be positioned in/or overthe opening 154. Or as an alternative the second container 144 could bea box having an attachable top 156. The second container also 144defines a container cavity 158 which is of a sufficient size to allowinsertion of the prepackaged configuration 12 of the piston assembly 18or a plurality thereof. The second container 144 is adapted to hold thecomponents firmly therein. A container seal 160 may be provided on thetop 156 of the second container 144 to engage the container wall 150when the top 156 is positioned over the opening 154. Additionally,alternate containers could be manufactured from foam, plastic or fibermaterials.

[0038] While the invention is susceptible to various modifications andalternative forms, a specific embodiment thereof has been shown by wayof example in the drawings and is herein described in detail. It shouldbe understood, however, that there is no intent to limit the inventionto the particular form disclosed, but on the contrary, the intention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

INDUSTRIAL APPLICABILITY

[0039] The prepackaged piston assembly 10 of the present invention isprepared in the following manner. Components including the piston member36 the plurality of rings 46 and the sleeve 30 are gathered andinspected for conformity to manufacturer's specifications. The pluralityof rings 46 are installed into the ring grooves 42 in the appropriatepositions. The plurality of rings 46 are compressed using a conventionalring compressor. Referring to the sleeve 30 of FIGS. 5 and 6, the sleeve30 is positioned around the piston member until the sleeve 30 contactsthe ring compressor. The sleeve 30 is pushed or pulled against the ringcompressor sliding the sleeve 30 over the plurality of rings 46. As thesleeve 30 slides over the plurality of rings 46 the ring compressorslides off of the plurality of rings 46. When the plurality of rings areconfined completely within the sleeve bore 54 the ring compressor isremoved from the piston member 68.

[0040] If the sleeve 30 of the embodiment of FIG. 6 is to be used, thestep of compressing the plurality of rings 46 would not require aconventional ring compressor. After the plurality of rings 46 areproperly positioned on lower portion of the piston member 36 the sleeve30 is positioned over the piston member 36 with the tapered portion 82toward the plurality of rings 46. The sleeve 30 is them moved toward theplurality of rings 46 wherein the tapered portion 82 compresses theplurality of rings 46 as it moves. Movement of the sleeve 30 is ceasedwhen the plurality of rings 46 are confined within the straight portion80 of the sleeve 30.

[0041] Referring to the alternate sleeve 30′ of FIGS. 7-10 the standardring compressor is not require and the following procedure is used.After the components have been inspected, the plurality of rings 46 areinstalled into the ring grooves 42. The strap 86 is wrapped around theplurality of rings 46 that were previously installed in the ring grooves42. The second end 96 of the strap 86 is mated with the latching member100 and pulled until the plurality of rings 46 are in the compressedposition. Once the plurality of rings 46 are in the compressed position,the latching member 100 is used to fix the variable inside diameter 90of the sleeve 30′ and maintain the plurality of rings 46.

[0042] A connecting rod 60 can be included with the piston assembly 10or attached by the mechanic, since the sleeve 30 does not interfere withaccess to the wrist pin bore 54. The piston assembly 10 is next insertedinto the a container 32 impregnated with a rust inhibitor and/orlubricant. Alternately, piston assembly may be coated with lubricantand/or rust inhibitor and vacuum sealed. The container 32 and rustinhibitor/lubricant protects the piston assembly 10 from environmentalcontaminants such as dirt and moisture during storage and transportationof the prepackaged piston assembly 18. The pre-packaged piston assembly12 can be positioned in a second container 144 to protect the pistonassembly 10 from physical damage such as breaking or scratching. Thesecond container 144 may be adapted to hold a plurality of pistonassemblies 10 in a pre-packaged configuration 12. However it is possibleto have a single container which is capable of protecting the all pistonassemblies 10 from all of the previously mentioned concerns. Thecontainer(s) 32,144 can additionally be sealed in a manner whichrequires breaking of the seal 140 when the prepackaged piston assembly18 is removed by the mechanic. Usage of the seal 140 verifies to themechanic that the piston assembly 10 has not been tampered with andconforms to the manufacturers' specifications.

[0043] After the engine block 16 has been prepared for assembly,installation of the pre-packaged piston assemblies 18 is accomplished bybreaking the seal 140 and opening the container 32. The pre-packagedpiston assembly 18 is then removed from the container 32. Although notrequired for the proper use of this invention, but desirable of adiligent mechanic, the position of the plurality of rings 36 may beverified through the transparent sleeve 30 or window 74. In this examplea connecting rod 60 is attached to the piston assembly 10. Thepre-packaged piston assembly 18 is now positioned above the respectivecylinder bore 26 waiting installation. The piston assembly 10 is nextlowered toward the cylinder bore 26 with the connecting rod 60 insertedfirst. The piston assembly 10 is further lowered toward and into thecylinder bore 26 until the bottom surface 66 of the sleeve 30 contactsthe top surface 20 of the engine block 16. When the sleeve 30 contactsthe block 16 the piston assembly 10 can be further inserted into thecylinder bore 26 by pushing on the top portion 38 of the piston member36 or by pulling on the connecting rod 60. After the plurality of rings46 have entered the cylinder bore 26 the sleeve 30 can be discarded.When all piston assemblies 10 have been installed into the engine 14 theremainder of the engine 14 components are assembled in a typicalfashion.

[0044] The sleeve 30 of the present invention can be manufactured in anumber of ways. Metal sleeves 30 can be machined from a removablecylinder liner by cutting the sleeves 30 to length and deburring the cutedges. Additionally sleeves 30 could be cut from a piece of tube or pipewith the proper inside diameter. A third method of manufacturing sleeves30 could include injection molding from a plastic or alternate material.

[0045] Primary considerations of manufacturing sleeves 30 is to select amaterial which is sufficiently rigid to resist distortion and thermalexpansion. Since there is typically only 0.002″ difference between theinside diameter of the cylinder bore 26 and the outside diameter 78 ofthe piston member 36 the material characteristics must allowmanufacturing to close tolerances. The cost of the selected material forthe sleeve 30 should also be inexpensive, thus allowing the sleeve 30 tobe discarded after a single use. Recycling sleeves 30 at this time doesnot appear to be a cost effective option since it would require theadded expense of transportation.

[0046] Thus is can be seen that using a piston assembly 10 in theprepackaged configuration 12 during the assembly of an engine 6increases quality of the rebuilt engine 14 by insuring that the pistonassembly meets or exceeds manufacturers' specifications. Quality of theengine 14 is also enhanced when because the piston assembly 10 is lesslikely to be contaminated by dirt or moisture. The cost of rebuilding anengine 14 using the prepackaged piston assembly 18 is reduced becausethe time required to assembly large quantities of piston assemblies 10in a factory setting is typically less than assembling small quantitiesin the field.

1-19 (cancelled).
 20. A piston assembly, comprising: a piston memberhaving a plurality of ring grooves therein; a plurality of ringspositioned within the ring grooves, the plurality of rings having anexpanded position and a compressed position; and, a sleeve beingpositioned about the piston member and the plurality of rings and havinga strap and a latching member, the strap and the latching member beingintegrally formed, the strap having a mating portion and a sleeveportion, the latching member being located on the sleeve portion forreceiving and maintaining the mating portion at and between first andsecond positions and at least one intermediate position located betweenthe first and second positions, the sleeve having an interior surfaceand a width, the interior surface of the sleeve being in contact withthe plurality of rings when in the second position, the width beinggreater or equal a distance defined by a distance between a top edge ofa first piston ring and a bottom edge of a second piston edge.
 21. Apiston assembly, as set forth in claim 20, the sleeve forming an insidediameter, the inside diameter being variable.
 22. A piston assembly, asset forth in claim 20, the latching member including a body portionhaving a slot, the mating portion being slidably coupled to the slot andincluding a friction portion, the slot forming at least one catch, thefriction portion being movable into and out of engagement with the atleast one catch.
 23. A piston assembly, as set forth in claim 21, thefriction portion including a plurality of ribs disposed on along asurface of the mating portion.
 24. A piston assembly, as set forth inclaim 20, latching member being composed of a plurality of a openingslocated in the sleeve portion, the mating portion including at least oneprotrusion extending from a surface of the mating portion.
 25. A pistonassembly, as set forth in claim 24, the plurality of openings being apredetermined distance apart.
 26. A piston assembly, as set forth inclaim 24, the at least one protrusion having a body portion and a headportion.
 27. A piston assembly, as set forth in claim 26, the bodyportion having a smaller diameter than the head portion.
 28. A pistonassembly, as set forth in claim 24, the at least one protrusion beingreceived within one of the plurality of openings.
 29. A piston assembly,as set forth in claim 20, the latching member including a body portionhaving a slot, the mating portion being slidably coupled to the slot,further comprising a rotatable cam disposed within the body portion andbeing pivotal between a first position and second position, the matingportion being movable within the slot when the cam is in the firstposition and being fixed with respect to the slot when the cam is in thesecond position.
 30. A piston assembly, as set forth in claim 29, themating portion being fixedly interposed between the cam and the slotwhen the cam is in the second position.
 31. A piston assembly, as a setforth in claim 29, wherein the cam including a lever portion.
 32. Apiston assembly, as set forth in claim 20, the latching member includinga body portion having a slot and a wedge member disposed within theslot, the wedge member being movable between a first position and asecond position, the mating portion being movable within the slot whenthe wedge is in the first position and being fixed with respect to theslot when the wedge is in the second position.
 33. A piston assembly, asset forth in claim 32, the mating portion being fixedly interposedbetween the wedge and the slot when the wedge is in the second position.34. A piston assembly, comprising: a piston member having a plurality ofring grooves therein; a plurality of rings positioned within the ringgrooves, the plurality of rings having an expanded position and acompressed position; and, a sleeve being positioned about the pistonmember and the plurality of rings and having a first end and a secondend, the sleeve including a friction portion on the first end and alatching member located on the second end for receiving and maintainingthe friction portion at first and second positions.
 35. A pistonassembly, comprising: a piston member having a plurality of ring groovestherein; a plurality of rings positioned within the ring grooves, theplurality of rings having an expanded position and a compressedposition; and, a sleeve being positioned about the piston member and theplurality of rings and having a first end and a second end, the sleeveincluding at least one protrusion on the first end and a plurality ofopenings located on the second end for receiving and maintaining the atleast one protrusion.
 36. A piston assembly, comprising: a piston memberhaving a plurality of ring grooves therein; a plurality of ringspositioned within the ring grooves, the plurality of rings having anexpanded position and a compressed position; a sleeve being positionedabout the piston member and the plurality of rings and having a firstend and a second end, the sleeve including a latching member having aslot located on the first end for receiving the second end; and arotatable cam rotatably coupled to the latching member and being pivotalbetween a locked position and an unlocked position, the second end beingadjustable with respect to the first end when the rotatable cam is inthe unlocked position and being fixed with respect to the first end whenthe rotatable cam is in the locked position.
 37. A piston assembly,comprising: a piston member having a plurality of ring grooves therein;a plurality of rings positioned within the ring grooves, the pluralityof rings having an expanded position and a compressed position; a sleevebeing positioned about the piston member and the plurality of rings andhaving a first end and a second end, the sleeve including a latchingmember having a slot located on the first end for receiving the secondend; and a wedge member disposed within the slot and being movablebetween a first position and a second position, the mating portion beingmovable within the slot when the wedge is in the first position andbeing fixed with respect to the slot when the wedge is in the secondposition.
 38. A piston assembly, comprising: a piston member having aplurality of ring grooves therein; a plurality of rings positionedwithin the ring grooves, the plurality of rings having an expandedposition and a compressed position; and, a sleeve being positioned aboutthe piston member and the plurality of rings and having a top surface, abottom surface and an outer wall, the sleeve having a sleeve bore formedby the top surface and the bottom surface, the sleeve bore having astraight portion extending from the bottom surface toward the topsurface and a tapered portion extending from a top end of the straightportion to the top surface.